NEW YORK, Feb 22 (Reuters Health) -- Italian scientists have figured out
how an episode of the television cartoon Pokemon may have caused epileptic
seizures in 685 Japanese children in 1997.
The problem was caused by an abnormal brain response in these children to
flashing lights featured in the cartoon, signaling a brain disorder known as
photosensitive epilepsy.
Dr. Vittorio Porciatti of the Institute of Neurophysiology in Pisa and
colleagues say that a mechanism in the brain that controls the reaction to
visual information "is defective or absent in" people with photosensitive
epilepsy.
It has been known for many years that strobe lights or flashing lights may
cause seizures in people with this type of epilepsy, but it was unclear how the
lights induced this response. In an attempt to understand that process,
Porciatti and colleagues exposed eleven patients with photosensitive epilepsy to
different patterns of flashing lights and studied the brainwaves of these
patients in response to the lights.
Compared with people who did not have the disorder, photosensitive
epileptics had abnormal brain activity in response to slow-flashing lights with
high contrast. These are the type of lights "common in TV images and in video
games, and may be important in triggering the abnormal (brain) response
underlying visually induced epileptic seizures," the researchers write in the
March issue of Nature Neuroscience.
The researchers note that while the disorder is not very common, affecting
between 0.5 - 0.8% of children between the ages of 4 - 14, they suspect that
photosensitive epilepsy "is increasing as a result of the proliferation of
television display units and video games, which may act as triggers."
